1. Field of the Invention
The present invention relates to a vehicle interior member that includes a covering material, having a double-layer structure including a lower layer that reflects infrared radiation and an upper layer that allows infrared radiation to pass therethrough.
2. Description of the Related Art
Existing vehicle interior members, such as an instrument panel, include a cushioning material that is disposed between a core material and a covering material, in order to provide a soft texture. The core material is made of a rigid resin or the like. The cushioning material is made of a polyurethane foam, a polystyrene foam, a foamed polyethylene, or the like. The covering material is made of a soft resin such as a polyvinyl chloride and a polyurethane. The covering material is usually dark colored, such as black, to make dirt inconspicuous and to improve the design. The surface of the covering material is textured by transferring an undulating pattern, such as a leather pattern and a geometric pattern, thereonto so as to provide the surface with a good design and a texture.
Carbon black is a known example of a pigment that gives the covering material a dark color. However, carbon black is easily heated by absorbing infrared radiation. When sunlight falls on the surface of the covering material during daytime even in the case of parking for just a short time, the temperature of the surface rises and heat radiation from the surface increases the cabin temperature. Therefore, when a passenger enters a vehicle after the vehicle has been parked for a long time in scorching sunlight in midsummer, the passenger feels discomfort, due to such high cabin temperature.
To prevent this, a substance that reflects infrared radiation may be mixed into the covering material in order to reduce absorption of infrared radiation. Metal oxides, such as a chromium oxide (Cr2O3) and a titanium oxide (TiO2), are known examples of a substance that reflects infrared radiation. However, such a metal oxide is white and significantly reflects light. Therefore, if such a metal oxide is used, for example, for a covering material of an instrument panel, an image of the instrument panel is reflected by the windshield, so that visibility during driving may be obstructed and light reflected by the covering material may dazzle a passenger.
To prevent this, Japanese Unexamined Patent Application Publication No. 2009-39153, for example, describes a technology related to a covering material, having a double-layer structure including a lower layer and an upper layer. The lower layer is made of a material containing a metal oxide, so that the lower layer serves as an infrared reflecting layer. The upper layer is made of a material containing a black pigment that is transmissive to infrared radiation, so that the upper layer allows infrared radiation to pass therethrough. Accordingly, infrared radiation that has passed through the upper layer is reflected by the lower layer, whereby absorption of infrared radiation is reduced.
With the technology described in Japanese Unexamined Patent Application Publication No. 2009-39153, the material of the upper layer contains a black pigment that is transmissive to infrared radiation. Therefore, the surface of the upper layer is dark colored, has a good design, and does not substantially reflect light. As a result, if an instrument panel has such an upper layer, an image is not substantially reflected by the windshield, so that visibility for a driver is not obstructed and a passenger is not dazzled.
However, with the technology described in Japanese Unexamined Patient Application Publication No. 2009-39153, the outer surface of the upper layer is textured and it is necessary that the upper layer has a thickness that is at least larger than the depths of depressed portions of the textured pattern. Therefore, the thickness of the covering material having the double-layer structure becomes large. If, for example, a cushioning material for the instrument panel is formed so as to have a conventional shape, the overall size of the instrument panel becomes large.
Moreover, because the textured pattern is usually formed on the surface of the upper layer by using shaping dies, it is necessary to form each of the lower layer and the upper layer of the covering material by using shaping dies, which makes the manufacturing process complex and increases the product cost.